This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to better understand the genetic control of early vertebrate tooth development. Several cell-signaling pathways are known to be necessary for proper tooth formation but the signals sufficient to induce de novo tooth development remain elusive. Employing a comparative phylogenetic approach, we seek to identify evolutionarily conserved genomic cis-regulatory sequences located in the vicinity of Dlx2, a gene expressed relatively early in vertebrate tooth development. We will then functionally test the ability of identified sequences to control gene expression during tooth development using transgenic reporter experiments in fish embryos. The identification of such elements will help us narrow down the list of candidate trans-acting genes near or at the top of the tooth initiation regulatory cascade. Finally, we will test the function of these candidate factors to induce tooth organogenesis in zebrafish embryos. The results from fish will likely be applicable to vertebrate tooth development in general and may facilitate future regenerative dental therapies in humans.